Ohio State cornerback Malcolm Jenkins said he returned for his senior season in part because he wanted to win a national championship.

His decision to delay his pro career gives the Buckeyes a much better chance of reaching that goal.

Jenkins probably would have been one of the first cornerbacks drafted had he chosen to turn pro after his junior season. His decision to return to school allows him to enter his senior year as the No. 1 defensive back in the Rivals.com Power Rankings, which measure the nation's top players and coaches at each position.

Jenkins, a 6-foot-1, 201-pounder from Piscataway, N.J., has earned first-team All-Big Ten honors in each of the past two seasons and was a Rivals.com second-team All-America pick in '07. His size and 4.3 speed in the 40-yard dash make him a likely first-round pick.

We're introducing our preseason power rankings on a position-by-position basis. We'll continue Thursday with the introduction of our special teams rankings.

The rating of a player and coach can fluctuate each week during the season depending on how they fared the previous week, but the power rankings measure overall career performances as well as their most recent results.

THE DEFENSIVE BACK RANKINGS

1. Malcolm Jenkins, Cornerback, Ohio State, Sr.The buzz: Jenkins could have been drafted in the first round if he had chosen to turn pro after his junior season. He instead opted to return and give Ohio State the nation's top cover corner. The four-year starter has earned first-team All-Big Ten honors each of the past two seasons.

2. William Moore, Free safety, Missouri, Sr.The buzz: Perhaps no defensive back in the nation put up the kind of numbers Moore delivered last season. Moore recorded 117 tackles and tied for the NCAA lead with a school-record eight interceptions. He scored on an interception return and forced a fumble in the Cotton Bowl and was named the game's defensive MVP.

3. Eric Berry, Strong safety, Tennessee, Soph.The buzz: Rated by Rivals.com as the No. 3 overall player in the 2007 recruiting class, Berry wasted no time living up to the hype. Berry was the first defensive player in the Phillip Fulmer era to start an opener as a true freshman. He forced two fumbles as a freshman and returned five interceptions for 222 yards.

4. Vontae Davis, Cornerback, Illinois, Jr.
The buzz: The versatile Davis blocked two punts and delivered a 63-yard kickoff return last season, but he does his best work on defense. The probable first-round pick – his brother, Vernon, was a first-round pick a few years ago out of Maryland – has excelled so much that the only question remaining about him is if he can maintain his focus. Illinois coach Ron Zook sent him a message by demoting him to the second team during spring practice.

5. Patrick Chung, Strong safety, Oregon, Sr.
The buzz: This four-year starter has averaged 97 tackles per season, including 117 a year ago. Chung needs only 45 more stops to become the leading tackler among defensive backs in school history. He's a hard hitter who also is effective enough in coverage to have eight career interceptions.

6. Alphonso Smith, Cornerback, Wake Forest, Sr.The buzz: Throw the ball in Smith's direction and risk the possibility of giving up six points. Smith tied for the NCAA lead with eight interceptions last season and returned three of them for touchdowns. He also led the ACC in pass breakups (18) and forced fumbles (four).

7. Taylor Mays, Free safety, USC, Jr.The buzz: Mays won a starting job as a true freshman and hasn't looked back. He recorded 65 tackles last season while emerging as one of the nation's hardest-hitting defensive backs. Mays had arthroscopic ankle surgery before spring practice, but the injury shouldn't bother him this season.

8. Victor Harris, Cornerback, Virginia Tech, Sr.The buzz: Harris is such an exceptional athlete that the Hokies are looking for ways to get him involved on offense. Harris didn't play offense last year, but he still scored touchdowns on an interception return and kickoff return. He finished his junior year with five interceptions and 11 pass breakups.

9. Derek Pegues, Free safety, Mississippi State, Sr.The buzz: Pegues developed into one of the SEC's top clutch players last season. He continually came up big in the Bulldogs' biggest moments. He scored on an interception return in an early season upset of Auburn and returned a punt 75 yards for a touchdown in a comeback victory over Ole Miss. After playing cornerback two years ago, Pegues moved to free safety last year and picked off five passes.

10. Emanuel Cook, Strong safety, South Carolina, Jr.The buzz: There might not be a better tackler in the SEC than Cook, a fierce hitter who made at least seven stops in each of the Gamecocks' final 10 games last season. Cook showed his toughness last season by playing against Georgia just two weeks after an appendectomy.

11. Mike Mickens, Cornerback, Cincinnati, Sr.The buzz: USF would rather not see this guy ever again. Mickens scored on a 79-yard interception return and broke up a pass in the end zone with two seconds remaining in the Bearcats' victory over USF last year. But this guy is no one-game wonder. He has earned All-Big East honors the past two seasons and picked off six passes a year ago.

12. D.J. Moore, Cornerback, Vanderbilt, Jr.The buzz: Moore tied for the SEC lead with six interceptions last season, the highest single-season total by a Vanderbilt player since 1982. He picked off two passes in an upset of South Carolina and finished the season with a team-high 63 solo tackles. Moore also set a school record last season with 823 yards in kickoff returns.

13. DeAngelo Smith, Cornerback, Cincinnati, Sr.The buzz: Smith and Mickens give Cincinnati arguably the nation's top cornerback duo. Smith tied for the NCAA lead with eight interceptions last season and picked off three passes in a Papajohns.com Bowl victory over Southern Miss. Smith and Mickens combined for 14 interceptions last season, the highest total of any Division I-A duo.

14. Brandon Hughes, Cornerback, Oregon State, Sr.The buzz: Hughes is entering his fourth year as a starter and has established a reputation as one of the best cornerbacks in the Pac-10, a league with no shortage of outstanding defensive backs. Hughes picked off two passes last season and broke up 12 more. Hughes also showed his ability to help out in run support by assisting on three tackles in a goal-line stand during the Beavers' upset of a California team that was ranked second in the nation at the time.

15. Rashad Johnson, Free safety, Alabama, Sr.The buzz: This former walk-on came on strong late last season and tied for the SEC lead with six interceptions while earning first-team all-conference honors from the league's coaches. Johnson recorded 94 tackles and closed the season with a 13-tackle effort in an Independence Bowl victory over Colorado.

16. Alterraun Verner, Cornerback, UCLA, Jr.The buzz: The only returning starter in UCLA's secondary already has six career interceptions. He picked off four passes last year and also had 75 tackles. Verner ranked 11th in the nation last season with 1.46 pass breakups per game.

17. Donovan Warren, Cornerback, Michigan, Soph.The buzz: Warren is the godson of former Chicago Bears safety Mark Carrier and the nephew of former Indianapolis Colts player Chuckie Miller. So it probably shouldn't have come as a surprise that Warren hardly seemed awed by his surroundings during his first year of big-time college football. Warren made 11 starts at cornerback as a true freshman and recorded 52 tackles.

18. Kevin Ellison, Strong safety, USC, Sr.The buzz: Ellison teams with Mays to give the Trojans two highly regarded, third-year starting safeties. Ellison has a total of 121 tackles over the past two seasons and earned first-team All-Pac-10 honors for his performance in '07.

19. Jairus Byrd, Cornerback, Oregon, Jr.The buzz: After only two seasons, Byrd already has 12 career interceptions, which puts him in a tie for second among active Division I-A players. Byrd also had 65 tackles last season and was named the Ducks' defensive player of the week after games against Stanford, Arizona and UCLA.

20. Michael Hamlin, Strong safety, Clemson, Sr.The buzz: The only four-year starter on Clemson's roster recorded 97 tackles last season. In two of his last three games, Hamlin compiled 10 solo tackles against Boston College and 14 total tackles (two for loss) in the Chick-fil-A Bowl.

21. Captain Munnerlyn, Cornerback, South Carolina, Jr.The buzz: He has established a reputation as one of the SEC's top cover corners. Although he's only 5-9, Munnerlyn has proved adept at defending receivers of all sizes. He capitalized on his 4.35 speed in the 40-yard dash and 34-inch vertical leap to pick off three passes last season for the fourth-ranked pass defense in the nation.

22. Nic Harris, Strong safety, Oklahoma, Sr.The buzz: Harris has proved he can make plays all over the field. He performed well enough in pass coverage last season to earn first-team All-Big 12 honors from the league's coaches. But he's also a force in the backfield: Harris tied for second on the team last year with 9.5 tackles behind the line of scrimmage.

23. Walter Thurmond III, Cornerback, Oregon, Jr.The buzz: The third Oregon player on this list picked off five passes and scored two defensive touchdowns last season. He already has 27 pass breakups in his college career. No Oregon player has broken up that many passes in his first two seasons since Alex Molden in 1992-93. How great an accomplishment is that? Molden went on to become the 11th overall pick in the 1996 NFL Draft.

24. Darius Butler, Cornerback, Connecticut, Sr.The buzz: This four-year starter stated his case as one of the nation's top shutdown corners last season by holding Louisville star Harry Douglas to 19 receiving yards. Butler has 140 career tackles, 10 interceptions and 22 pass breakups. He's the cousin of Baltimore Ravens running back Willis McGahee.

25. Courtney Greene, Free safety, Rutgers, Sr.The buzz: This four-year starter has averaged 100 tackles per season and has earned second-team All-Big East honors each of the past two years. Greene had 101 tackles last season to lead the team in that category for the second time.